CN112406229B - Biaxially oriented polyester film and process for producing the same - Google Patents

Abstract

The invention discloses a biaxial extension polyester film and a manufacturing method thereof. The biaxially oriented polyester film comprises a polyester resin base layer and a matte layer formed on the polyester resin base layer. The matte layer comprises, based on 100 wt% of the total weight of the matte layer: (1)50 to 95 wt% of a polyester resin matrix, and the inherent viscosity of the polyester resin matrix is between 0.5 to 0.8 dL/g; (2)0.01 to 5 wt% of high viscosity polyester resin, and the inherent viscosity of the high viscosity polyester resin is between 0.9dL/g and 1.1 dL/g; (3)0.3 to 40 wt% of a plurality of filler particles, and the average particle size of the plurality of filler particles is between 0.15 to 10 microns. Thereby, the biaxially stretched polyester film can exhibit a matte effect on one side, and the biaxially stretched polyester film as a whole can maintain good transparency.

Description

Biaxially stretched polyester film and method for producing the same

technical field

The present invention relates to a polyester film, in particular to a biaxially stretched polyester film and a manufacturing method thereof.

Background technique

Compared with the common casting film (Casting Film) and blown film (Blown Film) processes of general plastic films, the biaxially stretched polyester film (BOPET Film) obtained by the biaxially stretched film (Biaxially Oriented Film) film method, its performance Good, and the product is widely used, it is the main processing method of polyester film at present. However, the performance of the existing biaxially stretched polyester films in terms of physicochemical properties (such as dullness and transparency) still has many defects in some applications.

For example, US Patent No. 3,154,461 discloses a method of making biaxially oriented matte surface films from thermoplastics such as polyethylene terephthalate or polypropylene. Wherein, the film includes incompressible particles (eg, calcium carbonate or silicon dioxide) with a particle size ranging from 0.3 to 20 microns and a concentration ranging from 1 to 25 wt %. However, the dullness of the film is unsatisfactory for many applications.

German Patent No. 2353347 discloses a method for producing a milky polyester film having a one- or multi-layer structure. The method includes preparing a mixture of linear polyester particles containing 3 to 27% by weight of a homopolymer or copolymer of ethylene or propylene; then extruding the mixture into a film and quenching the film; then, passing the Orienting the film in directions perpendicular to each other orients the film and heat-sets the film. The disadvantage of this method is that the cut ears (essentially a mixture of polyester and ethylene copolymer or propylene copolymer) produced during the production of the film cannot be recycled for regrind because the cut ears would make The produced film suffers from the problem of yellowing. Therefore, this method of manufacture is not economical and the yellow film produced with regrind cutting ears is not acceptable to the market.

European Patent No. 0053498 discloses a biaxially oriented multilayer polyester film having a transparent base layer (B), and a further layer (A) having a matte appearance, and applied to the layer at least one side. The layer with a matte appearance consists essentially of a copolyester containing polyethylene terephthalate and inert inorganic particles having an average diameter of 0.3 to 20 microns. The concentration of the inert inorganic particles is 3 to 40% by weight, based on the total weight of the layer with a matt appearance. The film has a high degree of mattness (gloss less than 15) and a transparency of greater than 60%, however, the film is still insufficient in some application markets.

Therefore, the inventor felt that the above-mentioned defects could be improved, and Nate devoted himself to research and application of scientific principles, and finally came up with the present invention with a reasonable design and effectively improving the above-mentioned defects.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is to provide a biaxially stretched polyester film and a manufacturing method thereof aiming at the deficiencies of the prior art.

In order to solve the above technical problems, one of the technical solutions adopted by the present invention is to provide a biaxially stretched polyester film, including: a polyester resin base layer; and a matte layer formed on the polyester resin base layer On the surface of one side; wherein, based on the total weight of the matte layer is 100wt%, the matte layer comprises: (1) 50wt% to 95wt% of a polyester resin matrix; wherein, the polyester resin The intrinsic viscosity (Intrinsic Viscosity) of the matrix is between 0.5dL/g to 0.8dL/g; (2) 0.01wt% to 5wt% of the high-viscosity polyester resin; wherein, the high-viscosity polyester resin is dispersed in In the polyester resin matrix, and the intrinsic viscosity of the high-viscosity polyester resin is between 0.9 dL/g to 1.1 dL/g; (3) 0.3 wt % to 40 wt % of a plurality of filler particles; wherein , a plurality of the filler particles are also dispersed in the polyester resin matrix, and the average particle size of the plurality of the filler particles is between 0.15 microns to 10 microns.

Preferably, the polyester resin base layer has a thickness of 1 to 100 microns, and the matte layer has a thickness of 1 to 100 microns.

Preferably, the plurality of filler particles are further classified into: a plurality of first filler particles having a first average particle size; and a plurality of second filler particles mixed with a plurality of the first filler particles, and having a second average particle size; wherein, the first average particle size is between 0.15 microns and 2 microns, and the second average particle size is between 2 microns and 10 microns.

Preferably, the absolute value of the difference between the first average particle size and the second average particle size is not less than 1 micron.

Preferably, the surface of the side of the matte layer away from the polyester resin base layer has an average roughness (Ra) between 200 nm and 1,000 nm, and the whole of the biaxially stretched polyester film is It has a transparency of not less than 80%, a gloss of not more than 60%, and a haze of not less than 4%.

Preferably, the polyester resin base layer, the polyester resin matrix, and the high-viscosity polyester resin are all high-molecular polymers obtained by condensation polymerization of dibasic acid and dihydric alcohol; wherein , the material of the plurality of first filler particles and the material of the plurality of second filler particles are respectively selected from silicon dioxide, titanium dioxide, ceria, aluminum hydroxide, magnesium hydroxide, aluminum oxide, magnesium oxide, oxide Boron, calcium oxide, calcium carbonate, barium carbonate, strontium titanate, barium titanate, calcium titanate, magnesium titanate, calcium sulfate, barium sulfate, lithium phosphate, calcium phosphate, magnesium phosphate, boron nitride, aluminum nitride, At least one of the group consisting of carbon black, talc, kaolin, and cross-linked polymer particles.

Preferably, the polyester resin base layer contains a plurality of another filler particles, and the weight percentage concentration of the plurality of the another filler particles in the polyester resin base layer is lower than that of the plurality of the other filler particles in the matte layer. The weight percentage concentration of the filler particles, and the weight percentage concentration of a plurality of the other filler particles in the polyester resin base layer is not greater than the weight percentage concentration of a plurality of the filler particles in the matte layer. 20% of the concentration.

Preferably, the outer surface of the matte layer is defined as a matte surface, and the outer surface of the polyester resin base layer is defined as a flat surface; wherein, the matte surface roughness of the biaxially stretched polyester film is higher than The ratio of the roughness of the flat surface is not less than 1.5, and the ratio of the glossiness of the biaxially stretched polyester film to the glossiness of the flat surface is not more than 0.85.

The embodiment of the present invention also discloses a method for manufacturing a biaxially stretched polyester film, which includes: placing a polyester resin base material in a first extruder; and a plurality of filler particles are placed in a second extruder; the polyester resin base material placed in the first extruder, and all the materials placed in the second extruder The polyester resin matrix raw material, the high-viscosity polyester resin raw material, and a plurality of the filler particles are co-extruded by a co-extrusion method, so that the polyester resin base material is formed into a polyester resin base, and making the polyester resin matrix raw material, the high-viscosity polyester resin raw material, and a plurality of the filler particles together form a matte layer on one side surface of the polyester resin base layer; and the An unstretched polyester film composed of the polyester resin base layer and the matte surface layer is biaxially stretched to form a biaxially stretched polyester film; wherein, based on the total weight of the matte surface layer, it is 100wt% , the content range of the polyester resin matrix raw material is between 50wt% and 95wt%, the content range of the high viscosity polyester resin raw material is between 0.01wt% and 5wt%, and a plurality of the The content range of filler particles is between 0.3 wt % and 40 wt %; wherein, the inherent viscosity of the polyester resin matrix raw material is between 0.5 dL/g and 0.8 dL/g, and the high viscosity polyester The intrinsic viscosity of the resin raw material is between 0.9 dL/g and 1.1 dL/g, and the average particle size of the plurality of said filler particles is between 0.15 micrometers and 10 micrometers.

Preferably, the plurality of filler particles are further classified into: a plurality of first filler particles having a first average particle size; and a plurality of second filler particles mixed with the plurality of first filler particles and having a second average particle size; wherein the first average particle size is between 0.15 microns and 2 microns, the second average particle size is between 2 microns and 10 microns, and the first The absolute value of the difference between the average particle size and the second average particle size is not less than 1 micron.

Preferably, a plurality of the first filler particles and a plurality of the second filler particles are mixed with each other in a weight ratio ranging from 1:9 to 9:1, so that the plurality of the first filler particles and The mixture of a plurality of the second filler particles, the particle size distribution curve obtained by the dynamic light scattering method, exhibits a single peak distribution.

Preferably, a surface of the matte layer away from the polyester resin base layer has an average roughness (Ra) between 200 nanometers and 1,000 nanometers, and the whole of the biaxially stretched polyester film has a The transparency is less than 80%, the gloss is not more than 60%, and the haze is not less than 4%.

To sum up, the biaxially stretched polyester film disclosed in the embodiments of the present invention can be achieved through “the matte layer is formed on one side surface of the polyester resin base layer” and “based on the total weight of the matte layer is 100wt%, the matte layer comprises: (1) 50wt% to 95wt% polyester resin matrix; wherein, the intrinsic viscosity (IntrinsicViscosity) of the polyester resin matrix is between 0.5dL/g to 0.8dL/ between g; (2) 0.01wt% to 5wt% of high-viscosity polyester resin; wherein, the high-viscosity polyester resin is dispersed in the polyester resin matrix, and the inherent viscosity of the high-viscosity polyester resin is between 0.9 dL/g and 1.1 dL/g; (3) 0.3 wt % to 40 wt % of a plurality of filler particles; wherein a plurality of said filler particles are also dispersed in said polyester resin matrix, and The technical solution that the average particle size of the plurality of filler particles is between 0.15 micrometers and 10 micrometers”, so that the biaxially stretched polyester film can exhibit a matte effect on one side, and the The whole biaxially stretched polyester film can still maintain good transparency.

In order to further understand the features and technical content of the present invention, please refer to the following detailed description and accompanying drawings of the present invention, but these descriptions and drawings are only used to illustrate the present invention, rather than make any claims to the protection scope of the present invention. limit.

Description of drawings

1 is a schematic cross-sectional view of a biaxially stretched polyester film according to an embodiment of the present invention.

FIG. 2 is a partial enlarged view of area II of FIG. 1 .

3 is a flow chart of a method for manufacturing a biaxially stretched polyester film according to an embodiment of the present invention.

FIG. 4 is a schematic diagram of a co-extrusion extruder according to an embodiment of the present invention.

Detailed ways

The following are specific specific examples to illustrate the embodiments disclosed in the present invention, and those skilled in the art can understand the advantages and effects of the present invention from the contents disclosed in this specification. The present invention can be implemented or applied through other different specific embodiments, and various details in this specification can also be modified and changed based on different viewpoints and applications without departing from the concept of the present invention. In addition, the drawings of the present invention are merely schematic illustrations, and are not drawn according to the actual size, and are stated in advance. The following embodiments will further describe the related technical contents of the present invention in detail, but the disclosed contents are not intended to limit the protection scope of the present invention.

It should be understood that although terms such as "first", "second", "third" and the like may be used herein to describe various components or signals, these components or signals should not be limited by these terms. These terms are primarily used to distinguish one component from another component, or one signal from another. In addition, the term "or", as used herein, should include any one or a combination of more of the associated listed items, as the case may be.

[Biaxially stretched polyester film]

Please refer to FIG. 1 and FIG. 2 , this embodiment discloses a biaxially stretched polyester film 100 . The biaxially stretched polyester film 100 includes a polyester resin base layer 1 and a matte layer 2 formed on one surface of the polyester resin base layer 1 . The biaxially stretched polyester film 100 is formed by sequentially applying the polyester resin base layer 1 and the matte layer 2 through a co-extrusion process and a biaxial-stretching process.

The biaxially stretched polyester film 100 can present a matte effect on one side through the selection of the components of the matte layer 2 and the adjustment of the ratio formula. That is to say, a surface of the biaxially stretched polyester film 100 can exhibit a matte effect, and the whole of the biaxially stretched polyester film 100 can still maintain good transparency.

In order to achieve the above purpose, in this embodiment, the polyester resin base layer 1 has a thickness T1 of 1 to 100 microns, and preferably 10 to 100 microns. Furthermore, the material of the polyester resin base layer 1 is a high molecular polymer obtained by condensation polymerization of a dibasic acid and a dihydric alcohol or a derivative thereof. That is to say, the matrix material of the polyester resin base layer 1 is mainly polyester material. Preferably, the polyester material is polyethylene terephthalate (PET) or polyethylene naphthalate (PEN), but the present invention is not limited thereto. Thereby, the polyester resin base layer 1 can make the whole biaxially stretched polyester film 100 have good transparency, and can provide the matte layer 2 with good support. It should be noted that the polyester resin base layer 1 can also be added with filler particles as described below (not shown in the figure), and the weight percentage concentration of the filler particles in the polyester resin base layer 1 is lower than the following The weight percentage concentration of filler particles in the matte layer 2.

If the thickness T1 of the polyester resin base layer 1 is higher than the upper limit of the above-mentioned thickness range, the transparency of the biaxially stretched polyester film 100 will be deteriorated. On the contrary, if the thickness T1 of the polyester resin base layer 1 is lower than the lower limit of the above thickness range, the polyester resin base layer 1 cannot provide good support for the matte layer 2 .

It is worth mentioning that the raw material dibasic acid in the above-mentioned polyester material is terephthalic acid, isophthalic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid , 1,4-naphthalenedicarboxylic acid, bibenzoic acid, diphenylethanedicarboxylic acid, diphenylsulfone dicarboxylic acid, anthracene-2,6-dicarboxylic acid, 1,3-cyclopentanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, malonic acid, dimethylmalonic acid, succinic acid, diethyl 3,3-succinate, glutaric acid, 2,2-Dimethylglutaric acid, adipic acid, 2-methyladipic acid, trimethyladipic acid, pimelic acid, azelaic acid, sebacic acid, suberic acid, and dodecane at least one of the diacids. Furthermore, the above-mentioned raw material diols for forming the polyester material are ethylene glycol, propylene glycol, hexamethylene glycol, neopentyl glycol, 1,2-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, 1,10-decanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, and 2,2-bis(4-hydroxyphenyl) ) propane or at least one of bis(4-hydroxyphenyl)sulfone.

In order to achieve the above purpose, in this embodiment, the matte layer 2 has a thickness T2 ranging from 1 micrometer to 100 micrometers, and preferably from 5 micrometers to 85 micrometers.

If the thickness T2 of the matte layer 2 is higher than the upper limit of the above-mentioned thickness range, the transparency of the biaxially stretched polyester film 100 will be deteriorated. On the contrary, if the thickness T2 of the haze layer 2 is lower than the lower limit of the above thickness range, the haze of the haze layer 2 will become too low, so that the haze layer 2 cannot reach the desired value. desired physicochemical properties.

Further, the material composition of the matte layer 2 includes a polyester resin matrix 21 , a high-viscosity polyester resin 22 , and a plurality of filler particles 23 . Wherein, the high-viscosity polyester resin 22 and the plurality of filler particles 23 are uniformly dispersed in the polyester resin matrix 21 .

In terms of the content of each component, based on the total weight of the matte layer being 100 wt %, the content of the polyester resin matrix ranges from 50 wt % to 95 wt %, and the content of the high-viscosity polyester resin ranges from 50 wt % to 95 wt %. is between 0.01 wt % to 5 wt %, and the content of the plurality of filler particles 23 ranges from 0.3 wt % to 40 wt %, and preferably 0.3 wt % to 25 wt %.

In terms of the physicochemical properties of each component, the intrinsic viscosity (Intrinsic Viscosity, IV for short) of the polyester resin matrix 21 is between 0.5 dL/g and 0.8 dL/g. That is, the polyester resin matrix 21 is a polyester resin having an intermediate viscosity. Different from the polyester resin matrix 21, the intrinsic viscosity of the high-viscosity polyester resin 22 is between 0.9 dL/g and 1.1 dL/g.

According to the above-mentioned proportions of the polyester resin matrix 21 and the high-viscosity polyester resin 22 and the selection of the intrinsic viscosity, the matte layer 2 can pass through the difference in molecular weight between the polyester resin matrix 21 and the high-viscosity polyester resin 22. , different shrinkage rates, and poor compatibility, so that when a light passes through the matte layer 2, the light will be scattered by the matte layer 2, so that the biaxially stretched polyester film 100 can The single side has a matte effect, and the whole of the biaxially stretched polyester film 100 can still maintain good transparency.

However, if the content of the high-viscosity polyester resin 22 is higher than the upper limit of the above-mentioned content range (eg, higher than 5 wt %), the haze of the haze layer 2 will become too high, and the The high-viscosity polyester resin 22 also cannot be uniformly dispersed in the polyester resin matrix 21 (or, the matte layer 2 may cause problems during film formation), so that the overall biaxially stretched polyester film 100 transparency deteriorates. On the contrary, if the content of the high-viscosity polyester resin 22 is lower than the lower limit of the above-mentioned content range (eg, lower than 0.01 wt %), the haze of the matte layer 2 will become insufficient.

It is worth mentioning that, in the matte layer 2, the materials of the polyester resin matrix 21 and the high-viscosity polyester resin 22 are also mainly made of dibasic acid and dihydric alcohol or its derivatives through condensation polymerization. The polymer obtained by the reaction. That is to say, the materials of the polyester resin matrix 21 and the high-viscosity polyester resin 22 are also polyester materials. Since in the biaxially stretched polyester film 100 of this embodiment, the matrix materials used in the polyester resin base layer 1 and the matte layer 2 are all polyester materials, the biaxially stretched polyester film 100 can have Good productivity and processability. In addition, the cutting ear material produced in the production process of the biaxially stretched polyester film 100 can also be recycled into the production process as a recycled material, and the film made from the recycled material will not produce yellowing Phenomenon.

It is also worth mentioning that, in this embodiment, the intrinsic viscosity of the polyester material of the polyester resin base layer 1 is also between 0.5 dL/g and 0.8 dL/g. That is to say, the polyester material of the polyester resin base layer 1 is also a polyester resin with an intermediate viscosity, but the present invention is not limited thereto.

Further, in this embodiment, the average particle size of the plurality of filler particles 23 is between 0.15 microns and 10 microns, and based on the total weight of the matte layer is 100 wt %, the plurality of the The content of filler particles ranges from 0.3 wt% to 40 wt%.

In this way, the matte layer 2 can be further introduced by a plurality of filler particles 23, so that when a light passes through the matte layer 2, the light will be scattered by the matte layer 2, so that the double The axially stretched polyester film 100 can exhibit a matte effect on one side, and the whole of the biaxially stretched polyester film 100 can still maintain good transparency.

That is to say, the matte layer 2 of this embodiment can simultaneously pass the introduction of the high-viscosity polyester resin 22 and a plurality of filler particles 23, and the parameter selection of each component (including the selection of the content range and physicochemical properties), so that the The biaxially stretched polyester film 100 can exhibit a matte effect on one side, and the whole of the biaxially stretched polyester film 100 can still maintain good transparency.

In terms of dosage, if the content of a plurality of the filler particles 23 is higher than the upper limit of the above-mentioned content range (for example, higher than 40 parts by weight), the haze of the haze layer 2 will become too high, In addition, the plurality of filler particles 23 may not be uniformly dispersed in the polyester resin matrix 21 (or, the plurality of filler particles 23 may cause agglomeration), so that the biaxially stretched polyester film 100 The overall transparency is deteriorated. On the contrary, if the content of the plurality of filler particles 23 is lower than the lower limit of the above content range (eg, lower than 0.3 wt %), the haze of the haze layer 2 will become insufficient. In addition, in terms of the average particle size, when the average particle size of the plurality of filler particles 23 exceeds the upper limit of the average particle size, the overall transparency of the biaxially stretched polyester film 100 will be deteriorated. Conversely, if the average particle size of the plurality of filler particles 23 is lower than the lower limit of the average particle size, the surface roughness of the matte layer 2 will be too low.

Further, in an embodiment of the present invention, the plurality of filler particles 23 can be further classified into a plurality of first filler particles 231 and a plurality of second filler particles 232 according to the difference in average particle size. Wherein, a plurality of the first filler particles 231 and a plurality of the second filler particles 232 are mixed with each other, and a plurality of the first filler particles 231 have a first average particle size, and a plurality of the second filler particles 231 The filler particles 232 have a second average particle size.

Wherein, the first average particle size of the plurality of first filler particles 231 is between 0.15 μm and 2 μm, and the second average particle size of the plurality of second filler particles 232 is between 2 μm and 2 μm between 10 microns. Furthermore, the absolute value of the difference between the first average particle diameter of the plurality of first filler particles 231 and the second average particle diameter of the plurality of second filler particles 232 is not less than 1 μm, and preferably not less than 1 μm. 3 microns.

Wherein, in an embodiment of the present invention, the materials of the plurality of first filler particles 231 and the plurality of second filler particles 232 are all spherical or irregular granular silica, but the present invention is not limited to this. For example, the materials of the plurality of first filler particles 231 and the plurality of second filler particles 232 can be, for example, spherical or irregular particles of titanium dioxide, ceria, aluminum hydroxide, magnesium hydroxide, oxide Aluminum, magnesium oxide, boron oxide, calcium oxide, calcium carbonate, barium carbonate, strontium titanate, barium titanate, calcium titanate, magnesium titanate, calcium sulfate, barium sulfate, lithium phosphate, calcium phosphate, magnesium phosphate, nitride At least one of boron, aluminum nitride, carbon black, talc, kaolin, and cross-linked polymer particles.

It is also worth mentioning that, in an embodiment of the present invention, a plurality of the first filler particles 231 and a plurality of the second filler particles 232 are in a weight ratio between 1:9 and 9:1 The ranges are mixed with each other (or called blending), so that the mixture (or blending) of the plurality of the first filler particles 231 and the plurality of the second filler particles 232 is passed through the dynamic light scattering method (Laser Scattering) The obtained particle size distribution curve (Particle size distribution) presents a single peak distribution. Thereby, the uniformity of the surface roughness of the haze layer 2 can be effectively improved, and the biaxially stretched polyester film 100 can simultaneously achieve the effects of low gloss haze and high transparency.

According to the above configuration, the side surface 24 of the matte layer 2 away from the polyester resin base layer 1 (ie, the outer surface 24 of the matte layer 2 ) of the present embodiment has an average value between 200 nm and 1,000 nm. roughness (Ra), and the overall biaxially stretched polyester film 100 of this embodiment has a transparency of not less than 80%, a matte gloss of not more than 60% (preferably between 30 to 55%), and a haze of not less than 4% (preferably between 40 and 80%).

Based on the above physical and chemical properties, the biaxially stretched polyester film 100 of this embodiment is particularly suitable for use as a release film, a barrier film, or a special packaging.

Wherein, when the biaxially stretched polyester film 100 is used as a release film, a release agent can be coated on the matte layer 2 of the biaxially stretched polyester film 100 to be used as various types of resins (such as : Base material for thermoplastic polyurethane TPU, chlorinated polypropylene resin CPP) coating.

Wherein, when the biaxially stretched polyester film 100 is used as a barrier film, inorganic materials can be evaporated on the matte layer 2 of the biaxially stretched polyester film 100 to improve the effect of blocking moisture and gas.

Among them, since the biaxially stretched polyester film 100 has the characteristics of one-sided matt and high transparency, the biaxially stretched polyester film 100 is also particularly suitable for use as special packaging.

[Manufacturing method of biaxially stretched polyester film]

The above is the related description of the biaxially stretched polyester film 100 of the present embodiment, and the following will describe the manufacturing method of the biaxially stretched polyester film 100 according to the embodiment of the present invention.

Please refer to FIG. 3 and FIG. 4 , an embodiment of the present invention also discloses a method for manufacturing a biaxially stretched polyester film 100 . The manufacturing method of the biaxially stretched polyester film 100 includes step S110, step S120, step S130, and step S140. It must be noted that, the sequence of each step and the actual operation mode described in this embodiment can be adjusted according to requirements, and are not limited to those described in this embodiment.

Step S110 is to put the polyester resin base material 1' into a first extruder E1, and melt the polyester resin base material 1' at a high temperature (eg, a high temperature between 260°C and 300°C). Wherein, the intrinsic viscosity of the polyester resin base material 1' is between 0.5dL/g and 0.8dL/g, that is to say, the polyester resin base material 1' is a polyester resin with an intermediate viscosity .

Step S120 is placing the polyester resin matrix raw material 21', the high-viscosity polyester resin raw material 22', and the plurality of filler particles 23' into a second extruder E2, and extruding the polyester resin matrix raw material 21' , the high-viscosity polyester resin raw material 22 ′, and the plurality of filler particles 23 ′ are melted at high temperature (eg, high temperature between 260° C. and 300° C.) and kneaded with each other. Wherein, the intrinsic viscosity of the polyester resin matrix material 21' is between 0.5dL/g and 0.8dL/g, that is to say, the polyester resin matrix material 21' is also a polyester with an intermediate viscosity resin. In addition, the intrinsic viscosity of the high-viscosity polyester resin raw material 22' is between 0.9 dL/g and 1.1 dL/g, and the average particle size of the plurality of filler particles 23' is between 0.15 microns and 10 μm. between microns.

Step S130 is to put the polyester resin base material 1' placed in the first extruder E1, and the polyester resin base material 21' placed in the second extruder E2, the high-viscosity polymer The ester resin raw material 22' and a plurality of filler particles 23' are co-extruded by a co-extrusion (Co-Extrusion) method, and passed through a cooled drum E3 (eg, a drum cooled to 20°C to 50°C) Rapid cooling is performed so that the polyester resin base material 1' is formed into a polyester resin base layer 1, and the polyester resin base material 21', the high-viscosity polyester resin material 22', and the plurality of filler particles are formed 23' is formed as a matte layer 2 on one surface of the polyester resin base layer 1, so that the polyester resin base layer 1 and the matte layer 2 together constitute an unstretched polyester film 100'.

Step S140 is to biaxially extend the unstretched polyester film 100' formed by the polyester resin base layer 1 and the matte layer 2 to form a biaxially stretched polyester film 100 having a double-layer structure.

Wherein, the above-mentioned biaxial stretching method may be, for example, vertical uniaxial stretching method, horizontal uniaxial stretching method, vertical axis-horizontal axis sequential biaxial stretching method, or vertical axis-horizontal axis simultaneous biaxial stretching method. Not restricted. Furthermore, the above-mentioned biaxial stretching method can be, for example, preheating the unstretched polyester film 100 ′ at the stretching temperature of 50° C. to 150° C., and applying different stretching ratios to the unstretched polyester film 100 ′. ' in the width direction (or transverse direction, TD) of 2.0 times to 5.0 times, and preferably 3.0 times to 4.0 times of stretching processing, and further to the unstretched polyester film 100 ' is given 1.0 to 3.0 times of stretching, and preferably 1.0 to 2.5 times of stretching in the longitudinal direction (or, longitudinal direction, MD).

Wherein, based on the total weight of the matte layer 2 being 100 wt %, the content of the polyester resin matrix raw material 21 ′ ranges from 50 wt % to 95 wt %, and the content of the high-viscosity polyester resin raw material 21 ′ The content range is between 0.01 wt % and 5 wt %, and the content range of the plurality of filler particles 23 ′ is between 0.3 wt % and 40 wt %.

The biaxially stretched polyester film 100 prepared according to the above manufacturing method, the surface 24 of the side surface 24 of the matte layer 2 away from the polyester resin base layer 1 has an average roughness (Ra between 200 nm and 1,000 nm) ), and the whole of the biaxially stretched polyester film 100 has a transparency of not less than 80%, a glossiness of not more than 60% (preferably between 20 to 40%), and a fog of not less than 4% Spend.

[Experimental data test]

Hereinafter, the content of the present invention will be described in detail with reference to Exemplary Examples 1 to 4 and Comparative Examples 1 to 2. However, the following exemplary examples are provided only as an aid to understand the present invention, and the scope of the present invention is not limited to these exemplary examples.

The manufacturing methods of the biaxially stretched polyester films of the exemplary examples 1 to 4 and the comparative examples 1 to 2 can be manufactured by referring to the above steps S110 to S140. Among them, the proportion formula of each component and the process parameter conditions are arranged in Table 1 below.

Next, the physicochemical properties of the biaxially stretched polyester films prepared in Examples 1 to 4 and Comparative Examples 1 to 2 were tested to obtain the physicochemical properties of the biaxially stretched polyester films, such as: film surface roughness , and the overall transparency, gloss, and haze of the polyester film. The relevant test methods are described below, and the relevant test results are listed in Table 1.

Roughness test: According to JIS B0601, B0651 international standard test specifications, using a three-dimensional surface roughness meter (made by Kosaka Research Institute, trade name: SURF CORDER SE-3CK), at the tip of the stylus R2 μm, scanning pitch 2 μm, scanning length 1 mm, Under the conditions of 100 scanning lines, a cut-off value of 0.25 mm, and a magnification of 5,000 times, the average roughness of the center line of the surfaces of the biaxially stretched polyester films of Example Examples 1 to 4 and Comparative Examples 1 to 2 was tested ( Ra) and ten-point average roughness (Rz). The roughness listed in the table below is the centerline average roughness (Ra).

Transparency and haze test: According to JIS K7705 international standard test specifications, use Tokyo Denshoku Co., Ltd. Haze Meter, model TC-HIII, test the biaxially stretched polyester films of Example 1 to 4 and Comparative Examples 1 to 2. The transparency (light transmittance) and haze value.

Gloss test: According to the JIS Z 8741 international standard test specification, the gloss meter VGS-SENS0R manufactured by Nippon Denshoku Industry Co., Ltd. was used to test the gloss of the biaxially stretched polyester films of Example 1 to 4 and Comparative Examples 1 to 2 (G60). The test conditions were that the incident angle and the light receiving angle were both tested at 60° (N=5), and the average value thereof was used.

[Table 1 The proportions of ingredients and the test results of physicochemical properties of the example and the comparative example]

[Test results discussion]

According to the proportions, formulations and process parameters of the ingredients in Table 1, the polyester films with single-side haze of Examples 1 to 4 all have a transparency of not less than 80% and a haze glossiness of not more than 60%. Furthermore, when the thickness of the fog surface layer is thicker, the fog surface layer can use a lower content of filler particles, which can still obtain the same effect (for example: the thickness of the fog surface layer in Example 3 is 20 μm, and the filler particle content of the fog surface layer is 20 μm). The total content is 20 wt %; while the thickness of the matte layer of Example 4 is 80 μm, and the total content of filler particles is 1.2 wt %). It is worth mentioning that the polyester resin base layers in Example 2 to 4 are also added with a plurality of filler particles (eg, third filler particles and fourth filler particles) according to the design requirements of the product. The weight percentage concentration of the plurality of filler particles is lower than the weight percentage concentration of the plurality of filler particles in the matte layer, and the weight percentage concentration of the filler particles in the polyester resin base layer is not greater than that in the matte layer. 20% by weight of filler particles. In addition, the ratio of the matte surface roughness to the flat surface roughness of the polyester films of Example 1 to 4 is not less than 1.5, and is approximately between 1.5 and 4.5, and the matte surface gloss ratio is higher than the flat surface glossiness. The ratio is not greater than 0.85 and is approximately between 0.45 and 0.85. It should be noted that the above-mentioned "matte surface" refers to the outer surface of the matte surface layer, and the flat surface refers to the outer surface of the polyester resin base layer.

The polyester films of Comparative Examples 1 to 2 do not have a matte layer. Although the polyester film of Comparative Example has filler particles added to its polyester resin base layer, since the content of filler particles is less than 0.3 The transparency of the polyester film can be greater than 80%, but its gloss and haze are low, and cannot achieve the desired haze effect of the present invention.

[Advantageous effects of the embodiment]

The beneficial effect of the present invention is that the biaxially stretched polyester film provided in the embodiment of the present invention can be formed by "the matte layer 2 is formed on one side surface of the polyester resin base layer 1" and "based on the matte layer 1" The total weight of 2 is 100 wt %, and the matte layer 2 comprises: (1) 50 wt % to 95 wt % of a polyester resin matrix; wherein, the intrinsic viscosity (Intrinsic Viscosity) of the polyester resin matrix is between 0.5 between dL/g and 0.8dL/g; (2) 0.01wt% to 5wt% of a high-viscosity polyester resin 22; wherein the high-viscosity polyester resin 22 is dispersed in the polyester resin matrix 21, and The intrinsic viscosity of the high-viscosity polyester resin 22 is between 0.9 dL/g and 1.1 dL/g; (3) a plurality of filler particles 23 of 0.3 wt % to 40 wt %; wherein, a plurality of the filler particles 23 is also dispersed in the polyester resin matrix 21, and the average particle size of a plurality of the filler particles 23 is between 0.15 microns and 10 microns", so that the biaxially stretched polyester film 100 can exhibit a matte effect on one side, and the whole of the biaxially stretched polyester film 100 can still maintain good transparency.

Furthermore, in the biaxially stretched polyester film 100 of the embodiment of the present invention, the matrix materials used in the polyester resin base layer 1 and the matte layer 2 are all polyester materials, so the double The axially stretched polyester film 100 can have good productivity and processability. In addition, the cutting ear material produced in the production process of the biaxially stretched polyester film 100 can also be recycled into the production process as a recycled material, and the film made from the recycled material will not produce yellowing Phenomenon.

The above descriptions are only preferred and feasible embodiments of the present invention, and are not intended to limit the protection scope of the present invention. All equivalent changes and modifications made according to the claims of the present invention shall fall within the protection scope of the claims of the present invention. .

Claims (11)

1. A biaxially stretched polyester film, wherein the biaxially stretched polyester film comprises: a polyester resin base layer having a thickness of 1 micron to 100 microns; and a matte layer, formed on one side surface of the polyester resin base layer, the matte layer has a thickness of 1 micron to 100 microns; wherein, based on the total weight of the matte layer is 100wt%, the The matte layer includes: (1) 50wt% to 95wt% polyester resin matrix; wherein, the intrinsic viscosity (IntrinsicViscosity) of the polyester resin matrix is between 0.5dL/g and 0.8dL/g; (2) 0.01wt% to 5wt% of high-viscosity polyester resin; wherein, the high-viscosity polyester resin is dispersed in the polyester resin matrix, and the intrinsic viscosity of the high-viscosity polyester resin is between 0.9 Between dL/g and 1.1dL/g; (3) 0.3wt% to 40wt% of a plurality of filler particles; wherein a plurality of the filler particles are also dispersed in the polyester resin matrix, and the average particle diameter of the plurality of the filler particles is between 0.15 microns to 10 microns. 2. The biaxially stretched polyester film according to claim 1, wherein the plurality of filler particles are further divided into: a plurality of first filler particles having a first average particle size; and a plurality of second filler particles mixed with a plurality of the first filler particles and having a second average particle size; Wherein, the first average particle size is between 0.15 microns and 2 microns, and the second average particle size is between 2 microns and 10 microns. 3 . The biaxially stretched polyester film according to claim 2 , wherein the absolute value of the difference between the first average particle size and the second average particle size is not less than 1 μm. 4 . 4 . The biaxially stretched polyester film according to claim 2 , wherein the surface of the matte layer on the side away from the polyester resin base layer has an average value between 200 nm and 1,000 nm. 5 . Roughness (Ra), and the biaxially stretched polyester film as a whole has a transparency of not less than 80%, a gloss of not more than 60%, and a haze of not less than 4%. 5 . The biaxially stretched polyester film according to claim 2 , wherein the polyester resin base layer, the polyester resin base, and the high-viscosity polyester resin are all made of dibasic acid. 6 . A high molecular polymer obtained by condensation polymerization with a dihydric alcohol; wherein, the materials of the plurality of first filler particles and the materials of the plurality of second filler particles are respectively selected from silica, titania, and silica Cerium, aluminum hydroxide, magnesium hydroxide, aluminum oxide, magnesium oxide, boron oxide, calcium oxide, calcium carbonate, barium carbonate, strontium titanate, barium titanate, calcium titanate, magnesium titanate, calcium sulfate, barium sulfate, At least one selected from the group consisting of lithium phosphate, calcium phosphate, magnesium phosphate, boron nitride, aluminum nitride, carbon black, talc, kaolin, and cross-linked polymer particles. 6 . The biaxially stretched polyester film according to claim 1 , wherein the polyester resin base layer contains a plurality of another filler particles, and a plurality of the another filler particles in the polyester resin base layer. 7 . The weight percentage concentration of the particles is lower than the weight percentage concentration of the plurality of filler particles in the matte layer, and the weight percentage concentration of the plurality of the other filler particles in the polyester resin base layer is different. More than 20% of the weight percent concentration of the plurality of filler particles in the matte layer. 7. The biaxially stretched polyester film according to claim 1, wherein the outer surface of the matte layer is defined as a matte surface, and the outer surface of the polyester resin base layer is defined as a flat surface; Wherein, the ratio of the roughness of the biaxially stretched polyester film to the roughness of the upper flat surface is not less than 1.5, and the ratio of the glossiness of the matte surface of the biaxially stretched polyester film to the gloss of the upper flat surface is not less than 1.5. greater than 0.85. 8. A method for producing a biaxially stretched polyester film, wherein the method for producing the biaxially stretched polyester film comprises: Putting the polyester resin base material into a first extruder; Putting the polyester resin matrix raw material, the high-viscosity polyester resin raw material, and a plurality of filler particles into a second extruder; The polyester resin base material to be placed in the first extruder, and the polyester resin base material and the high-viscosity polyester resin material to be placed in the second extruder , and a plurality of the filler particles are co-extruded by a co-extrusion method, so that the polyester resin base material is formed into a polyester resin base layer, and the polyester resin base material, the high-viscosity polymer an ester resin raw material, and a plurality of the filler particles together form a matte layer on one side of the polyester resin base layer; and biaxially extending an unstretched polyester film formed by the polyester resin base layer and the matte layer to form a biaxially stretched polyester film; Wherein, the polyester resin base layer has a thickness of 1 to 100 microns, and the matte layer has a thickness of 1 to 100 microns; Wherein, based on the total weight of the matte layer is 100wt%, the content range of the polyester resin matrix raw material is between 50wt% and 95wt%, and the content range of the high viscosity polyester resin raw material is between between 0.01 wt % and 5 wt %, and the content of the plurality of filler particles ranges from 0.3 wt % to 40 wt %; Wherein, the inherent viscosity of the polyester resin matrix raw material is between 0.5dL/g to 0.8dL/g, and the inherent viscosity of the high viscosity polyester resin raw material is between 0.9dL/g to 1.1dL/g and the average particle size of the plurality of filler particles is between 0.15 microns and 10 microns. 9. The method for producing a biaxially stretched polyester film according to claim 8, wherein the plurality of filler particles are further divided into: a plurality of first filler particles having a first average particle size; and a plurality of second filler particles mixed with a plurality of the first filler particles and having a second average particle size; Wherein, the first average particle diameter is between 0.15 micrometers to 2 micrometers, the second average particle diameter is between 2 micrometers and 10 micrometers, and the first average particle diameter is the same as the second average particle diameter. The absolute value of the difference between the two average particle sizes is not less than 1 micron. 10 . The method for producing a biaxially stretched polyester film according to claim 9 , wherein a plurality of the first filler particles and a plurality of the second filler particles are in a ratio of 1:9 to 9:1. 11 . The weight ratio ranges therebetween are mixed with each other, so that the mixture of the plurality of first filler particles and the plurality of second filler particles, the particle size distribution curve obtained by the dynamic light scattering method, exhibits a single peak distribution. 11 . The method for producing a biaxially stretched polyester film according to claim 9 , wherein a surface of the matte layer away from the polyester resin base layer has a thickness between 200 nm and 1,000 nm. 12 . Average roughness (Ra), and the biaxially stretched polyester film as a whole has a transparency of not less than 80%, a gloss of not more than 60%, and a haze of not less than 4%.

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